system-configur-packages --isodir出错

mang003

system-configur-packages   - -isodir=/media/cdrom

错误信息如下 :
[root@localhost ~]# system-config-packages --isodir=/media/cdrom/
Traceback (most recent call last):
  File "/usr/share/system-config-packages/MainWindow.py", line 160, in ?
    im = get_method(args)
  File "/usr/share/system-config-packages/config.py", line 57, in get_method
    return method.LoopbackIsoInstallMethod(isodir)
  File "/usr/share/system-config-packages/method.py", line 352, in __init__
    self.mountDisc(1)
  File "/usr/share/system-config-packages/method.py", line 403, in mountDisc
    self.tree + "/" + self.discImages[discNum],
KeyError: 1

请高手指点一下